This invention relates generally to RF amplifiers and, more particularly, to an RF amplifier arrangement for providing output signals having a controlled or modified frequency distribution.
In many applications, such as radar systems, for example, it is desirable to control the output signal spectrum of a transmitter in order to concentrate the output power in the frequency bands needed to implement a desired function. For the radar example this might be to match the output signals spectrum to a required task, such as providing unique waveforms for special signal processing and/or minimizing interference with nearby radars (friendly interference).
One approach to obtaining such frequency spectrum control is by directly attenuating the high power output of a transmitter that is being operated in saturation. This requires using large components to handle the high power and such components are generally more expensive, larger, heavier, hotter operating, slower operating, and less reliable than components that operate at the lower power of the input signal drive to the transmitter. Spectrum control at the output of the high power RF amplifier is consequently not generally tried because of problems with handling the power at the device's output.